I’m not sure how to word what I mean.
What things are helpful to know about when making 3D things, but that you don’t immediately think of?
Knowing how cameras and lenses work can help quite a bit, and optics in general. Color theory is another thing, since it can help you understand why your lights/colors may look off and how exactly to tweak them.
I always sketch out ideas quickly before doing anything, like plotting a plan. I know some people don’t do that and end up with half the idea they had.
Photography is a great hobby for a 3D artist. As mentioned an interest in programming if only just to understand how computers work. I’d add to that geometry, algebra and trigonometry. I think a good understanding of physics would be useful for an animator or VFX artist.